Oceanographic Seawater Properties

Oceanographic Seawater Properties (TEOS-10)

Usage

1. MCP Server Definition

import asyncio
import json
from contextlib import AsyncExitStack
from mcp.client.streamable_http import streamablehttp_client
from mcp import ClientSession

class OceanGSWClient:
    """Ocean GSW (Gibbs SeaWater) MCP Client"""

    def __init__(self, server_url: str, api_key: str):
        self.server_url = server_url
        self.api_key = api_key
        self.session = None

    async def connect(self):
        print(f"Connecting to: {self.server_url}")
        try:
            self.transport = streamablehttp_client(
                url=self.server_url,
                headers={"SCP-HUB-API-KEY": self.api_key}
            )
            self._stack = AsyncExitStack()
            await self._stack.__aenter__()
            self.read, self.write, self.get_session_id = await self._stack.enter_async_context(self.transport)
            self.session_ctx = ClientSession(self.read, self.write)
            self.session = await self._stack.enter_async_context(self.session_ctx)
            await self.session.initialize()
            print("✓ connect success")
            return True
        except Exception as e:
            print(f"✗ connect failure: {e}")
            return False

    async def disconnect(self):
        """Disconnect from server"""
        try:
            if hasattr(self, '_stack'):
                await self._stack.aclose()
            print("✓ already disconnect")
        except Exception as e:
            print(f"✗ disconnect error: {e}")
    def parse_result(self, result):
        try:
            if hasattr(result, 'content') and result.content:
                content = result.content[0]
                if hasattr(content, 'text'):
                    return json.loads(content.text)
            return str(result)
        except Exception as e:
            return {"error": f"parse error: {e}", "raw": str(result)}

2. Seawater Properties Calculation Workflow

Calculate seawater thermodynamic properties following the TEOS-10 (Thermodynamic Equation of Seawater - 2010) international standard.

Workflow Steps:

1. Convert to Absolute Salinity - Convert practical salinity to absolute salinity
2. Calculate Density - Compute seawater density
3. Calculate Sound Speed - Determine speed of sound in seawater
4. Calculate Freezing Temperature - Find freezing point
5. Calculate Conservative Temperature - Get conservative temperature from potential temperature

Implementation:

## Initialize client
client = OceanGSWClient(
    "https://scp.intern-ai.org.cn/api/v1/mcp/34/OceanGSW-Tool",
    "<your-api-key>"
)

if not await client.connect():
    print("connection failed")
    exit()

print("=== Oceanographic Seawater Properties (TEOS-10) ===\n")

## Input parameters for typical ocean conditions
practical_salinity = 35.0  # PSU (practical salinity units)
temperature = 10.0          # °C (in-situ temperature)
pressure = 1000.0           # dbar (approximately 1000m depth)
longitude = -30.0           # degrees E
latitude = 20.0             # degrees N

## Step 1: Convert practical salinity to absolute salinity
print("Step 1: Convert to Absolute Salinity")
result = await client.session.call_tool(
    "SA_from_SP",
    arguments={
        "SP": practical_salinity,
        "p": pressure,
        "lon": longitude,
        "lat": latitude
    }
)
absolute_salinity = client.parse_result(result)
print(f"Practical Salinity: {practical_salinity} PSU")
print(f"Absolute Salinity: {absolute_salinity} g/kg\n")

## Step 2: Calculate seawater density
print("Step 2: Calculate Seawater Density")
result = await client.session.call_tool(
    "rho",
    arguments={
        "SA": absolute_salinity,
        "CT": temperature,
        "p": pressure
    }
)
density = client.parse_result(result)
print(f"Density: {density} kg/m³\n")

## Step 3: Calculate speed of sound
print("Step 3: Calculate Sound Speed")
result = await client.session.call_tool(
    "sound_speed",
    arguments={
        "SA": absolute_salinity,
        "CT": temperature,
        "p": pressure
    }
)
sound_speed = client.parse_result(result)
print(f"Sound Speed: {sound_speed} m/s\n")

## Step 4: Calculate freezing temperature
print("Step 4: Calculate Freezing Temperature")
result = await client.session.call_tool(
    "t_freezing",
    arguments={
        "SA": absolute_salinity,
        "p": pressure,
        "saturation_fraction": 0.0  # 0 for air-free, 1 for air-saturated
    }
)
freezing_temp = client.parse_result(result)
print(f"Freezing Temperature: {freezing_temp}°C\n")

## Step 5: Calculate potential temperature
print("Step 5: Calculate Potential Temperature")
result = await client.session.call_tool(
    "pt_from_t",
    arguments={
        "SA": absolute_salinity,
        "t": temperature,
        "p": pressure,
        "p_ref": 0.0  # Reference pressure (0 for surface)
    }
)
potential_temp = client.parse_result(result)
print(f"In-situ Temperature: {temperature}°C")
print(f"Potential Temperature: {potential_temp}°C\n")

await client.disconnect()

Tool Descriptions

OceanGSW-Tool Server (TEOS-10 Standard):

• SA_from_SP: Convert practical salinity to absolute salinity

  • Args: SP (PSU), p (dbar), lon (deg E), lat (deg N)
  • Returns: Absolute salinity (g/kg)

• rho: Calculate seawater density

  • Args: SA (g/kg), CT (°C), p (dbar)
  • Returns: Density (kg/m³)

• sound_speed: Calculate speed of sound in seawater

  • Args: SA (g/kg), CT (°C), p (dbar)
  • Returns: Sound speed (m/s)

• t_freezing: Calculate freezing temperature

  • Args: SA (g/kg), p (dbar), saturation_fraction (0-1)
  • Returns: Freezing temperature (°C)

• pt_from_t: Calculate potential temperature from in-situ temperature

  • Args: SA (g/kg), t (°C), p (dbar), p_ref (dbar)
  • Returns: Potential temperature (°C)

Input/Output

Inputs:

• Practical Salinity (SP): PSU (practical salinity units), typically 32-37 for open ocean
• Absolute Salinity (SA): g/kg, accounts for non-salt materials
• Temperature (t, CT): °C, in-situ or conservative temperature
• Pressure (p): dbar, approximately equal to depth in meters
• Longitude: degrees East
• Latitude: degrees North

Outputs:

• Absolute salinity: g/kg
• Density: kg/m³
• Sound speed: m/s
• Freezing temperature: °C
• Potential temperature: °C

Use Cases

• Oceanographic research and monitoring
• Climate modeling and ocean circulation studies
• Underwater acoustics and sonar applications
• Marine biology habitat characterization
• Ocean engineering and offshore operations
• Fisheries science
• Sea level and ocean heat content studies

TEOS-10 Overview

TEOS-10 (Thermodynamic Equation of Seawater - 2010) is the international standard for seawater properties:

• Replaces the older EOS-80 standard
• Uses Absolute Salinity instead of Practical Salinity
• Uses Conservative Temperature instead of Potential Temperature
• Provides consistent thermodynamic framework
• Essential for accurate ocean property calculations

Physical Interpretations

Absolute vs Practical Salinity:

• Practical Salinity: Based on conductivity measurement
• Absolute Salinity: Mass fraction of dissolved material (includes non-salt components)
• Difference typically ~0.5 g/kg but varies regionally

Seawater Density:

• Increases with salinity and pressure
• Decreases with temperature
• Typical ocean: 1020-1030 kg/m³
• Critical for ocean circulation and stratification

Sound Speed:

• Increases with temperature, salinity, and pressure
• Typical ocean: 1480-1540 m/s
• Critical for sonar, acoustic communication, seismic studies

Freezing Temperature:

• Decreases with salinity
• Increases with pressure (unusual property)
• Seawater freezes at ~-2°C at surface

Additional Ocean Tools

The OceanGSW-Tool server provides 50+ TEOS-10 functions including:

• alpha: Thermal expansion coefficient
• beta: Haline contraction coefficient
• chem_potential_water: Chemical potential
• cp: Specific heat capacity
• enthalpy: Specific enthalpy
• entropy: Specific entropy
• internal_energy: Specific internal energy
• Nsquared: Brunt-Väisälä frequency (ocean stability)
• sigma0, sigma1, sigma2, sigma3, sigma4: Potential density anomalies
• spiciness0, spiciness1, spiciness2: Water mass spiciness

Pressure Conversion

• 1 dbar ≈ 1 meter depth (very close approximation)
• Surface pressure: 0 dbar
• 1000 m depth: ~1000 dbar
• 10000 m depth (Mariana Trench): ~10000 dbar